Transcript
Energy from Waste
Research Paper 97/42
27 March 1997
The Non-Fossil Fuel Obligation and the Scottish Renewables Obligation impose requirementson public electricity suppliers to pay premium prices, funded by the Fossil Fuel Levy, forelectricity from renewable energy developers. Projects for generating electricity from wastecontinue to be awarded a significant number of the contracts resulting from these obligations.This paper provides an overview of alternative energy in the UK, with a focus on wasteincineration and landfill gas.
Grahame DanbyScience and Environment Section
House of Commons Library
Library Research Papers are compiled for the benefit of Members of Parliament and theirpersonal staff. Authors are available to discuss the contents of these papers with Members
d h i ff b d i b f h l bli
Summary
The recovery of energy from waste has been an important component of the UK's sustainabledevelopment strategy. In addition to managing waste more effectively, it contributessignificantly to targets for generating electricity from renewable energy sources. The principalfinancial mechanism for supporting this latter aim is the Non-Fossil Fuel Obligation whichimposes requirements on public electricity suppliers to contract for specified amounts ofgenerating capacity. Above market prices are paid to the successful renewable energydevelopers for a specified period, funded by a Fossil Fuel Levy which is reflected inelectricity bills.
This paper provides an overview of the current state of renewable energy in the UK, andsummarises the policies of the three largest political parties. Well over half of the nation'srenewable energy utilisation in 1995 came from waste. Details are provided on thetechnology, environmental impact and potential for the two most important waste to energymethods: municipal waste incineration and the collection of landfill gas. The paper ends witha brief summary of biogas from sewage sludge and animal wastes.
CONTENTS
Page
I UK policy on waste and renewable energy 7
A. Waste 7B. Renewable energy 8C. Non-Fossil Fuel Obligations 9D. Current status of renewables and prospects 11
II Waste incineration 15
A. Resource 15B. Technology 15C. Environmental factors 17D. Current status and prospects 18E. Planning 18
III Landfill gas 20
A. Resource 20B. Technology 20C. Environmental factors 21D. Current status and prospects 21
IV Sewage gas and animal wastes 23
A. Sewage gas 23B. Animal waste 23
V Further reading 24
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I UK policy on waste and renewable energy
A. Waste
The Government's strategy for non-radioactive solid wastes and sludges was set out in theDecember 1995 white paper Making Waste Work: A strategy for sustainable wastemanagement in England and Wales (Cm 3040). Three key objectives form the focus of thestrategy:
• to reduce the amount of waste that society produces;
• to make best use of the waste that is produced; and
• to choose waste management practices which minimise the risks of immediate andfuture environmental pollution and harm to human health.
A "waste hierarchy" has been drawn up to help classify the different waste managementoptions in general terms. From the environmental standpoint, reducing the quantity of wasteproduced in the first place is - other things being equal - the most desirable option. Afterwaste reduction, re-use (such as refilling bottles) is considered the next best environmentaloption. The Government attaches broadly equal importance to the three methods ofrecovering value from materials which have entered the waste stream; these methods arerecycling, composting, and energy. A focus of the present paper will be methods of obtainingenergy from waste. The fourth and least desirable waste management option is consideredto be disposal. Government waste strategy has accordingly been informed in part by theRoyal Commission on Environmental Pollution's 17th Report which recommended that1:
"wherever possible avoid creating waste, where wastes are unavoidable recycle them ifpossible and where wastes cannot be recycled ... recover energy from them"
It has been estimated that the UK produces 435 million tonnes of waste each year: 245million tonnes of controlled2 waste (household, industrial and commercial) and 190 milliontonnes of other waste (mostly from agricultural, mining and quarrying activity). About 70%of all controlled waste in England and Wales is landfilled, some of which will have been pre-treated in incinerators; these can obtain a 90% reduction in the volume of waste requiringdisposal. Most incinerators are currently engaged in the destruction of hazardous waste whichis unsuitable for landfilling.3
1 Royal Commission on Environmental Pollution - 17th Report, Incineration of Waste HMSO 19942 Environmental Protection Act 1990, section 753 Cm 3040, page 67
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A full discussion of UK waste management has been given in Landfill (House of CommonsLibrary Research Paper 96/103, 8 November 1996). Of great relevance to the potentialdevelopment of energy from waste schemes are the two primary targets which theGovernment have already set for England and Wales in order to take forward their wastestrategy. These targets have been termed "landfill diversion" and "recovery". The first targetis to reduce the proportion of controlled waste going to landfill to 60% by 2005. This impliessome increase in the amount of waste from which value is recovered. The second primarytarget is to recover 40% of municipal waste by 2005. Municipal waste includes all householdwaste, street cleaning waste and some commercial and trade waste.4 About 20 million tonnesof household waste are generated annually in the UK.5
B. Renewable energy
Renewable energy is a term used to describe energy sources which, for all practical purposes,are continually replenished.6 Examples include wind farms for generating electricity, solarpanels for water heating, and biodiesel as a transport fuel. The renewable status of wood forheat and electricity will depend on whether new trees are planted to replace those burnt. Sucha definition of renewable energy may seem to exclude energy from waste schemes, thoughmuch waste is biological in origin, and the sources of this could in principle be farmedsustainably.
On 31 March 1994, the former energy minister Mr Tim Eggar announced the publication ofNew and Renewable Energy:Future Prospects in the UK (Energy Paper 62). This was theGovernment's response to a report by the Renewable Energy Advisory Group, chaired by DrMartin Holdgate.7 Energy Paper 62 sets out a strategy to help establish a market foothold forkey renewables, including wood coppice, energy from waste, wind turbines and solar. Thisis in line with government policy:
"to stimulate the development of new and renewable energy sources wherever they haveprospects of being economically attractive and environmentally acceptable in order tocontribute to:
- diverse, secure and sustainable energy supplies;- reduction in the emission of pollutants;- encouragement of internationally competitive industries.
In doing this it will take account of those factors which influence business competitivenessand work towards 1,500 MW DNC of new electricity generating capacity from renewablesources for the UK by 2000."
4 Cm 3040, pp8-95 Digest of Environmental Statistics No. 18 1996, chapter 76 Renewable Energy House of Commons Library Research Paper 93/83, 29 July 19937 Renewable Energy Advisory Group: Report to the President of the Board of Trade (Energy Paper Number
60, November 1992)
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The figure of 1,500 megawatts Declared Net Capacity is similar to the electricity generatingcapacity of a large conventional power station. Declared Net Capacity takes into account theintermittent nature of some renewable sources, such as wind farms, by reducing the maximumcapacity (in megawatts) that the plant could maintain without sustaining damage.8 For a windfarm, the DNC is considered to be 43% of the rated output whereas energy from waste plantshave a DNC equal to the rated capacity. In other words, the same as conventional baseloadpower stations fired by fossil fuels (coal, gas, oil) or uranium.
The strategy for promoting renewables takes the form of a research, development,demonstration and dissemination (RDD&D) programme9,10, and the Non-Fossil FuelObligation for those electricity generating technologies closest to being commerciallycompetitive. There are several other programmes11 of relevance to renewable energy,including the EC's JOULE12 and THERMIE initiatives which provide funding for,respectively, research & development and demonstration projects13. The EC Commission hasproduced a green paper for a Community renewable energy strategy14 which contains detailednational comparisons, and promises of a more detailed strategy and action plan by mid-1997.One EC response to the challenge of increasing the contribution of renewables has beenALTENER15, a five year promotional programme ending this year, though there exists aproposal for an extension (ALTENER II).
C. Non-Fossil Fuel Obligations
Under section 32 of the Electricity Act 1989, the Secretary of State may require by order thatpublic electricity suppliers arrange to have available to them generating capacity from non-fossil fuel sources. Thus the following fuels are excluded: coal, coal products, lignite, naturalgas, crude liquid petroleum or petroleum products. The order may specify non-fossilgenerating stations of a particular description such as wind farms, different energy from wastetechnologies or nuclear power stations. A recent example of a non-fossil fuel obligation isthe Electricity (Non-Fossil Fuel Sources) (England and Wales) Order SI 1997/248. This isthe fourth renewables order (NFFO-4) for England and Wales, and like the other three itspurpose is to support various renewable energy technologies by requiring the public electricitysuppliers to contract for specified power capacity. A premium price (determined by a biddingprocess involving putative generators) is paid for electricity generated from these energysources.
8 Renewable Energy: Power for a Sustainable Future Open University 19969 The Renewable Energy Research, Development and Demonstration Programme National Audit Office 28
January 199410 The Renewable Energy Research, Development and Demonstration Programme Committee of Public
Accounts HC 387 1993/9411 http://www.etsu.com/DTIExportsGuide/programm.htm12 New Review ETSU/DTI February 199713 New Review ETSU/DTI November 199614 Energy for the Future: Renewable Sources of Energy COM(96) 576, 20 November 199615 European Environment vol 5 1995, pp58-60
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Details of the procedure have been summarised on page 127 of The Energy Report (DTI1996, volume 1). Essentially four steps are involved in making a NFFO renewables order inEngland and Wales:
1. A DTI Minister makes an announcement of the basic policy proposals for a newNFFO Order, including its overall size (in megawatts) and the technology bandslikely to be included. The DTI publishes further guidance to the 12 RegionalElectricity Companies in the form of a Renewable Energy Bulletin16.
2. Prospective NFFO generators prepare proposals to supply electricity, usingtechnologies specified in the Bulletin, and submit these to the Non-Fossil PurchasingAgency which acts on behalf of the RECs. These proposals are scrutinised by theOffice of Electricity Regulation (Offer) which applies to them a "will secure" test toassess their prospects of technical and economic feasibility17. Generators who passthe test can then submit formal bids to the NFPA.
3. After consulting Offer and the RECs, the Minister makes an Order setting anobligation on each REC for each technology band for each year of the Order. TheNFPA signs sufficient contracts so that individual RECs will secure the specifiedcapacity.
4. Before they can begin generating electricity, the contracted projects must obtain thenecessary consents: planning permission and, in the case of waste incinerators,authorisations18 under the Environmental Protection Act 1990. Operational projectssell their electricity to the RECs at an above market price, the difference beingfunded by the Fossil Fuel Levy.
Similar procedures exist in respect of a Scottish Renewables Obligation19,20,21 (SRO) and aNorthern Ireland Non-Fossil Fuel Obligation22 (NI-NFFO).
The premium prices paid to renewable energy electricity generators are funded by a fossil fuellevy which is payable by all licensed suppliers, and passed on to consumers as a percentageof their electricity bills. Condition 3 of the PES licence, which sets out the restrictions oncharges made by the public electricity supplier, makes provision for the fossil fuel levy.
16 Renewable Energy Bulletin No 6: Fourth Round of Bidding - NFFO-4 DTI December 199517 Fourth Renewables Order for England and Wales Offer January 199718 Processes subject to Integrated Pollution Control: Waste Incineration IPC Guidance Note S2 5.01,
Environment Agency, October 199619 HC Deb 13 March 1997 cc313-4W20 Outline Proposals for a Scottish Renewables Obligation A discussion paper issued by the Energy Division
of the Scottish Office Industry Department, May 199221 Scottish Renewables Obligation: Bulletin. Information about the Scottish Renewables Obligation for
Generators of Electricity from Renewable Energy Sources (Scottish Office Industry Department, October1993)
22 HC Deb 24 July 1996 cc474-5W
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The levy rate for England and Wales is determined according to the prescription given in theFossil Fuel Levy Regulations SI 1990/266 (as amended by SI 1996/1309). In Scotland, therelevant regulations are the Fossil Fuel Levy (Scotland) Regulations SI 1996/293 (as amendedby SI 1996/1512). The Director General of Electricity Supply collects the levy, using theproceeds to reimburse the public electricity suppliers for the excess costs involved inpurchasing renewable electricity from generators. Section 33 of the Electricity Act 1989
provides the general terms of reference under which the levy operates. Though the Electricity(Northern Ireland) Order SI 1992/231 (NI 1) includes provisions for a levy to support thedevelopment of non-fossil fuel sources such as renewables, such a levy has not beenintroduced. Instead, Northern Ireland Electricity is obliged by the Office for Regulation ofElectricity & Gas (OFREG) to meet its NI-NFFO obligations by the most economic means23.
In England and Wales, the fossil fuel levy rate currently stands at 3.7% (applied to electricitybills), though this will be reduced to 2.2% on April 1 1997. This will finance renewableenergy commitments and payments due to the non-privatised part of the nuclear industry24.The proportion of levy receipts going to renewables has steadily increased since 1990,reaching £99m in 1995/96, or 9% of the levy proceeds25 (which at that time stood at 10% onelectricity bills, to which VAT is then added26). From April 1, the levy rate for Scotland willrise 0.2% to 0.7%, to enable Scottish Power and Hydro-Electric to meet the additional costsof the Scottish Renewables Obligation27.
D. Current status of renewables and prospects
Most present day UK renewable energy output is in the form of electricity (2% of UKelectricity in 1995), with the national picture being dominated by large scale hydro andmunicipal solid waste combustion. Landfill gas and sewage sludge digestion together withother waste digestion or combustion make up most of the remaining renewable electricitysupply. Wind turbines and small scale hydro contributed only 4% to the supply of renewableelectricity (1995 figures), though they make a relatively greater contribution to replacing fossilfuel use. Detailed information is available from a number of sources, most particularly theDigest of United Kingdom Energy Statistics 1996 (DTI/Government Statistical Service July1996) and the Renewable energy statistics database28.
23 OFREG spokesman 21 March 199724 Offer press release R67/96, 20 December 199625 New Review February 1997. A lower figure of "some £94 million" was cited for 1995/96 in DTI press
release P/97/11626 In other words, one pays VAT on the levy. (source: Offer spokeswoman, 20 March 1997)27 Scottish Office press notice AG120/96, 20 December 199628 http://www.etsu.com/Renewables/RESTATS/home.htm
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The estimated total operational capacity of renewable-energy based electricity plant which wasoperational in the UK at the end of 1995 has been given in a written answer29:
large scale hydro 1,440 MW dnc30
other capacity outside non-fossil fuel obligations31 20 MW dnccapacity supported by non-fossil fuel obligations 380 MW dnc
As noted earlier, the present Government's policy is to work towards 1,500 MW of newrenewables-based capacity by 2000. Should this target be met, then the total renewables-based electricity generating capacity would come to about 3,000 MW dnc, equivalent tobetween 2 and 3 large thermal (e.g coal, nuclear) power stations.
Recent figures for renewable energy projects supported by non-fossil fuel obligations aregiven in the table below32,33:
obligation number ofcontracts
capacity ofcontractedprojects (MW)
number ofprojectsgenerating
capacity ofgeneratingprojects (MW)
NFFO-134 75 152.11 63 141.82
NFFO-235 122 472.23 82 179.79
NFFO-336 141 626.91 30 79.48
NFFO-437,38 195 843.1 - -
SRO-139 30 76.5 7 19.1
SRO-240,41 26 112 - -
NI-NFFO-142 20 15.6 11 12.4
NI-NFFO-243 10 16.27 1 0.75
29 HC Deb 9 January 1996 cc10-11W30 megawatts declared net capacity. A megawatt is a unit of power (not energy) which is equal to 1,000
kilowatts. Declared net capacity is a correction factor to take into account the intermittent nature of somerenewable energy sources.
31 NFFO/SRO/NI-NFFO32 Fourth Renewables Order for England and Wales Offer January 199733 Northern Ireland Office, Belfast (21 March 1997)34 SI 1990/185935 SI 1991/249036 SI 1994/3259, amended by SI 1995/6837 SI 1997/24838 DTI press notice P/97/116, 6 February 199739 SI 1994/327540 SI 1997/79941 HC Deb 13 March 1997 cc313-4W42 SR 132 (1994)
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The projects awarded contracts in the most recent England and Wales order (NFFO-4) havean average44 electricity price of 3.46 pence per kilowatt-hour, which compares with the 4.35pence achieved in NFFO-3.45 The size of a fifth order, currently planned for 1998, isexpected to take into account progress made in the earlier orders covering periods beyond thatyear (NFFO-3, NFFO-4).
Prospects for the further development of renewable energy will depend to some extent on theoutcome of the forthcoming general election. At the time of writing, the election manifestosof the larger parties were unavailable, but the use of non-fossil fuel obligations by the presentGovernment will reflect Conservative Party opinion.
The Labour Party has published a report of its policy commission on the environment calledIn trust for tomorrow (1994), which includes a chapter on a sustainable energy policy.Continued use of the fossil fuel levy is proposed to help meet a Labour Government's targetsof 10% of electricity demand to be met by renewables by 2010, and 20% by 2025. Thisgeneral policy aim was reiterated by Mr John Battle at a renewables conference in March1996. A report in Renew contained further details of Mr Battle's contribution46:
He added "Because our support for renewables is so low, Britain is being held back fromestablishing a competitive renewables industry. We are being held back from the futureindustries of the next century. Already we have lost ground by failing to encourage a UK windturbine industry early on in the expansion of the industry." He concluded "What's lacking isa strong framework of support to ensure that renewables, wind, biomass, wave and solar, canmove out of the margins and have a positive future as part of a diverse and sustainable longterm energy supply" and proposed that the NFFO, the bulk of which has gone to supportnuclear power, be converted into a 'Cleaner Energy levy' to support renewables.
Liberal Democrat policy on renewables is summarised on one of that Party's web pages47:
The UK should use the 'window' provided by plentiful supplies of cheap gas over the next10–15 years to invest in energy efficiency improvements and to develop renewable energysources to meet 20% of electricity demand within 15 years. We would encourage renewablesby:
Extending the current Non-Fossil Fuel Obligation.Increasing financial support for renewables through the Fossil Fuel Levy.Increasing spending on research and development.
43 SR 407 (1996)44 weighted according to their capacity45 DTI press notice P/97/116, 6 February 199746 http://eeru-www.open.ac.uk/NATTA/RENEW96(4).html, extracts from RENEW Issue 10147 http://www.libdems.org.uk/libdems/cgi-bin/show.pl?english+uk&../english/documents/uk/poli00429447.txt
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The Non-Fossil Fuel Obligation has provided a significant impetus to the development ofrenewable energy sources, and a similar competitive support mechanism is now being set upin France. The competitive element, has driven down prices to the extent that the averageprice paid for renewables in NFFO-3 was 4.35 pence per unit (kilowatt-hour), which comparesfavourably with the 6.5 pence per unit for NFFO-1 projects. The ongoing fall in prices (interms of money of the day) owes much to the longer contract lengths offered in the laterrenewables rounds, giving developers up to 15 years of premium prices with which to provideinvestors with the required rate of return. This is particularly important given the relativelyhigh capital cost of renewable energy technologies, in comparison with their running costs.
The Non-Fossil Fuel Obligation mechanism has been criticised, on account of the wastefulnessinvolved in its oversubscription (in the NFFO-3 round, only 27% of bids were awardedcontracts), and its lack of coordination with the planning system. Dr Catherine Mitchell ofSussex University's Science Policy Research Unit has written on this, and recommended arange of additional measures including green taxes and further incentives for renewableenergy development48.
48 Science & Public Affairs Winter 1996; Energy Policy vol 23, no 12, 1995
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II Waste incineration
A. Resource
In terms of electricity generation, combustion of municipal solid waste (MSW) is the mostimportant resource, accounting for 298.8 thousand tonnes of oil equivalent in 199549. Thisis broadly equivalent to the amount of oil which would have to be burned in a typical oil-firedstation to generate the same amount of electricity. Though tonnes of oil equivalent may seema rather strange way of measuring electrical energy, it is chosen largely by convention andfacilitates comparisons between different fuel types. Additional contributions come from theincineration of specialised wastes such as poultry litter50 and old tyres51,52, but these will notbe discussed in this paper.
Although MSW combustion is relatively important from the standpoint of electricity supply,only a small proportion is incinerated, the bulk going to landfill sites. The term MSWincludes all household wastes, together with wastes deposited at civic amenity sites, and aproportion of the waste from industry and commerce: a total of some 30 million tonnes peryear in the UK53. A further 20 million tonnes of General Industrial and Commercial Wastes(GIW) are also produced, consisting of items such as paper, cardboard, wood and plastics.GIW tends to have a higher calorific value (energy content) than MSW, though energyrecovery from it has mostly been for providing heat rather than electricity.
B. Technology
For the purposes of the third renewables order in England and Wales (NFFO-3), an eligiblewaste incinerator is one which is fuelled wholly or partially by municipal and/or industrialwaste and/or fuel derived from this waste54. One can use untreated MSW delivered by wastecarrying vehicles, as in the Edmonton incinerator supported by NFFO-1. Alternatively, onemay first process the waste, mechanically separating non-combustibles such as metal andglass, and then producing pellets of the remaining organic matter. The resulting product isknown as coarse RDF (refuse derived fuel). Densified refuse-derived fuel, d-RDF, is morehighly processed, pulverised, compressed and dried, and has 60% of the energy content, percubic metre, of coal55.
49 Digest of United Kingdom Energy Statistics 1996 (DTI/Government Statistical Service)50 "Poultry Litter as a Fuel in the UK" CADDET Renewable Energy Newsletter July 199351 "Scrap Tyres as a Fuel in the UK" CADDET Renewable Energy Newsletter January 199452 Making Waste Work Cm 3040 December 199553 Renewable Energy: A Commercial Opportunity ETSU/DTI 199454 Renewable Energy Bulletin No 5 DTI October 199355 Renewable Energy: Power for a Sustainable Future Open University 1996
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Because RDF has a much higher energy content for a given volume, it is cheaper to transportthan untreated waste. Furthermore, the reduced ash content of RDF and d-RDF means thatthey can be burned in conventional power stations along with coal56. The design of furnacesor boilers for burning waste alone will have to take a number of factors into account,including the relatively greater proportion (compared to coal) of volatile matter in waste. Oneclearly wants this to burn in the furnace rather than escape up the chimney. The boiler isused to heat water, producing steam which drives the electricity generating turbines. At theSELCHP plant in south east London, gases and particulates (fine particles of soot, smoke anddust) emerging from the incinerator are cleaned to remove dioxins and heavy metals,neutralise acids, and filtered to collect the dust. Finally, ferrous metals can be separated forrecycling from the residual ash using magnets. SELCHP was the first large-scale mass-burn57
incinerator to be built under the non-fossil fuel obligation (NFFO-2), and its designincorporated a combined heat and power element. If and when this element becomesoperational, waste heat from the steam will be channelled to provide useful heating forbuildings rather than being lost58.
Recently, explicit provision has been made for combined heat and power schemes to receivefossil fuel levy support. The powers to do this are contained within schedule 22, paragraph38 of the Environment Act 1995. In Renewable Energy Bulletin No 6 (DTI, December 1995)one of the technology bands identified as being eligible for support under the fourth (Englandand Wales) round of bidding (NFFO-4) was "municipal and industrial waste with combinedheat and power". NFFO-4 allows up to ten per cent59 of the incinerator fuel mix to consistof sewage.
Though the NFFO mechanism can only provide, by virtue of the Electricity Act, a premiumprice for the electrical output, the technology band has been defined in such a way as torequire an annual heat output and "reasonable prospects" of obtaining contracts for its supplyfor specified purposes. It is arguable whether one needed legislation to allow this support forCHP, though the 1995 Act certainly ended any doubt.
In addition to the CHP technology band mentioned above, NFFO-4 also specified "municipaland industrial waste by fluidised bed combustion". Fluidised bed furnaces are of a relativelysimple design, have high combustion efficiencies, and result in lower emissions of nitrogenoxides (which contribute to acid rain). They work by injecting the fuel into a "bed" of ashor sand which is supported and agitated by air flowing up through the base of the furnace60,61.
56 Cofiring of coal and waste IEA Coal Research, August 199657 mass-burn means burning the waste as collected.58 CADDET Renewable Energy Newsletter June 199459 on a "dry-weight" basis.60 Processes subject to Integrated Pollution Control: Waste Incineration Environment Agency October 199661 McGraw-Hill Encyclopedia of Engineering second edition
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C. Environmental factors
On 1 December 1996, an EC Municipal Waste Incineration Directive62 came into force,imposing more stringent emission standards which resulted in the closure of several existingplants63. To operate, municipal waste incinerators need to meet emission requirements whichare enforced by means of authorisations granted by the Environment Agency. The Agencyhas issued a guidance note64 on waste incineration which is a process prescribed for IntegratedPollution Control in regulations65 made under section 2 of the Environmental Protection Act
1990. Page 11 of the Environment Agency's guidance summarises the standards andobligations imposed by EC municipal waste directives, as implemented in the UK. Limitsare placed on emissions of dust, hydrogen chloride, carbon monoxide, hydrogen fluoride,sulphur dioxide, various heavy metals, and volatile organic compounds. A further ECdirective has been drafted for the incineration of non-hazardous waste which would imposestill stricter limits66.
The Department of the Environment's booklet, Energy from Waste (November 1996),acknowledges public concern about incinerator emission, but points to the new controls byway of reassurance. The booklet points to an Environment Agency report67 as havingdemonstrated that dioxin emissions from waste incinerators operating under the new standardswill not pose a health risk to people living near them. It is unlikely that this will entirelyreassure environmental groups like Friends of the Earth who have campaigned against newincinerators, favouring instead waste minimisation and recycling68. One advantage ofrecovering energy from municipal waste is that it could displace the use of fossil fuels,thereby preserving non-renewable resources and slowing the build up of atmospheric carbondioxide which has been implicated in global warming. Incineration greatly reduces thevolume of the waste, leaving a relatively inert residue which can be sent to a landfill site.
62 89/429/EEC (89/369/EEC applies to new waste incineration plants)63 ENDS Report November 199664 Processes subject to Integrated Pollution Control: Waste Incineration IPC Guidance Note S2 5.01,
Environment Agency October 199665 The Environmental Protection (Prescribed Processes and Substances) Regulations SI 1991/472 (as amended)66 "Energy from waste - progress to date and the barriers faced" Wastes Management May 199667 Risk Assessment of Dioxin Releases from Municipal Waste Incineration Processes DOE report
HMIP/CPR2/41/1/181 199668 http://www.foe.co.uk/camps/indpoll/index.html
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D. Current status and prospects
The table below shows how the price, in pence per kilowatt-hour, of electricity from wastecombustion has fallen, in the context of the Non-Fossil Fuel Obligation in England and Wales.Data is given for successful bids for NFFO contracts69,70.
number of projects capacity (MW) bid price (p/kWh)
NFFO-1 4 40.63 5.06 - 6.00
NFFO-2 10 271.48 5.50 - 6.55
NFFO-3 20 241.87 3.48 - 4.00
NFFO-4 16 241.3 2.66 - 3.4
The table clearly indicates that developers of incineration plants with energy recovery havebeen able to bid progressively lower prices for their electricity, the newer bids approachingthe market price for electricity sold on the national grid. What the table does not show isthe number of plants which were unable to take up their contracts due to the length of timeit took to obtain planning permission. Only two of the NFFO-2 incinerators were operationalas at December 1996, the remaining eight projects having been cancelled. While earlierrenewables rounds could only offer premium prices up to the year 1998, NFFO-3 introduced15-year contracts with a five year take-up period. Notwithstanding the new emission controls,it is anticipated that a result of this will be an expansion of incineration capacity comingonline. The December 1996 figure for operational NFFO-supported electricity from wasteincineration plants was about 100MW, enough for about 100,000 homes71.
E. Planning
In 1993 the Department of the Environment and the Welsh Office published Planning Policy
Guidance Note: Renewable Energy, which was supplemented in October 1994 by annexescovering energy from waste combustion, landfill gas, anaerobic digestion, hydro power, woodfuel, and active solar systems. Also of relevance is Planning Policy Guidance Note 23 (July1994) which deals with planning and pollution control.
69 DTI press release P/97/116, 6 February 199770 Fourth Renewables Order for England and Wales Offer, January 199771 Energy from Waste DOE November 1996
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In order to identify the main planning and environmental issues associated with thedevelopment of alternative energy sources, An Assessment of the Potential Renewable Energy
Resource in Scotland was published in December 1993. The study was carried out byScottish Hydro-Electric, Scottish Power, the Department of Trade and Industry, the ScottishOffice, Scottish Enterprise and Highlands and Islands Enterprise, with support from theConvention of Scottish Local Authorities. By way of putting renewable energy in the contextof the planning system, chapter 3 states:
"The land use planning system is intended to promote the sustainable use of land resourcesand to strike a balance between development and preservation of the environment. Planningpermission will be required for most renewable energy projects. Areas or sites that aretechnically suitable for renewable energy exploitation may not be acceptable to the planningauthority; the planning system will therefore influence the distribution of renewable energyexploitation across Scotland."
The above study was followed, in August 1994, by two Scottish Office publications: National
Planning Policy Guideline NPPG 6 (Renewable Energy) and Planning Advice Note PAN 45(Renewable Energy Technologies). The former provides a statement of Government policywhile the latter is designed to provide advice on good practice and other relevant information.NPPG 6 attempts to reconcile the Government's stated policy to promote renewable energyfor global environmental reasons with the protection of local environments and Scotland's ownnatural heritage. Paragraph 25 of the guidance is reproduced below:
Accordingly, in relation to renewable energy developments, planning authorities should seekthrough their policies and decisions:
• to provide positively for renewable energy developments, where this can be achievedin an environmentally acceptable manner;
• to safeguard sites with potential for renewable energy projects against sterilisation bytypes of development that would prevent or hinder such projects and could beaccommodated elsewhere;
• to protect areas of important natural and built heritage from inappropriate forms ofdevelopment;
• to achieve acceptable operating standards during the working life of any project andthe early restoration of sites, once operation has permanently ceased.
Installations for the disposal of industrial and domestic waste, and industrial installations forthe production of electricity, steam and heat are included in Schedule 2 of the Environmental
Assessment (Scotland) Regulations SI 1988/1221 (as amended). This means that anenvironmental assessment is required if the projects are likely to have significantenvironmental effects on account of their nature, size and location. Environmentalassessments are likely to be needed for all the municipal waste incinerators under construction(in England and Wales), given that the capacity of each exceeds an indicative criterion of75,000 tonnes per annum.
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III Landfill gas
A. Resource
The Department of the Environment's Energy from waste booklet states, in the context of thebulk of municipal solid waste:
"For much of this waste, it will be more sustainable to recover value from it at an energy fromwaste plant rather than to dispose of it by landfilling ...
... Energy can also be generated less directly from municipal solid waste from the methane gasproduced at landfill sites. However, while this approach has merit, it produces only one-fifthof the energy per tonne from municipal solid waste compared with an energy from waste[incinerator] plant, and has other disadvantages associated with it. It cannot therefore be seenas a substitute for the approach described here."
As already noted, the bulk of municipal waste goes to landfill sites, a consequence of thehistorically large number of suitable sites and the wide variety of wastes which can bedisposed of conveniently in this way. Despite the much greater volume of landfill wastecompared to that sent to incinerators, less electricity is generated by burning the gas given off:a UK total of 185.5 thousand tonnes of oil equivalent in 199572.
B. Technology
The disposal of municipal solid wastes in deep landfills, such as former quarry sites, providessuitable conditions for anaerobic digestion73. This is the process whereby a mixed populationof bacteria, which are ordinarily present, breaks down the organic matter in the refuse toproduce a mixture of gases, mostly comprising methane and carbon dioxide. Historically, thislandfill gas was burned off to minimise the risk of fire or explosion. Since the 1970sattention has focused on how to exploit this product for its energy value.
Developing a landfill site for energy recovery involves covering the waste with a layer ofimpervious clay to encourage anaerobic digestion which, as the name implies, takes place inthe absence of air. A network of interconnected perforated pipes is buried at depths of up to20 metres to collect the gas which is then burned in gas engines or turbines to drive electricitygenerators. A large modern landfill site can produce useful amounts of gas for over 15years74.
72 Digest of United Kingdom Energy Statistics 199673 Renewable Energy: Power for a Sustainable Future Open University 1996
74 New and Renewable Energy: Future Prospects in the UK, DTI March 1994
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C. Environmental factors
The emission of methane gas from a landfill site provides a notable environmental detrimentin that it contributes to the atmospheric greenhouse effect responsible for global warming.Leakage of the methane gas from the landfill site into buildings also poses an explosionhazard, though the risk could be minimised by careful engineering of the site and/or thecontrolled extraction of methane gas for heating or electricity generation. Burning the landfillgas destroys methane which is a highly potent greenhouse gas, replacing it with carbondioxide which is less so. Traffic movements relating to the transportation of waste to thelandfill site, and the associated vehicle emissions, may also be a cause for concern in the localcommunity. Landfill gas plants also raise questions relating to visual intrusion, mostly dueto the on-site equipment and gas flares.
In addition to planning permission for the use of the land, a landfill site requires a wastemanagement licence under Part II of the Environment Protection Act 1990. The EnvironmentAgency, as the waste regulation authority, has responsibility for monitoring a site once it hasclosed and for issuing a completion certificate. The development of a landfill site shouldordinarily involve the preparation of an environmental assessment. Whether this applies tothe subsequent development of an associated electricity generating plant will largely dependon its installed capacity75.
D. Current status and prospects
The table below shows the range of prices bid by successful landfill gas developers underdifferent rounds of the England and Wales renewables orders76,77. The data displayed isanalogous to that in section II D above.
number of projects capacity (MW) bid price (p/kWh)
NFFO-1 25 35.5 3.6 - 6.4
NFFO-2 28 48.45 3.96 - 5.7
NFFO-3 42 82.07 3.29 - 4.00
NFFO-4 70 173.7 2.8 - 3.2
75 Renewable Energy Technologies PAN45, Scottish Office, August 199476 DTI press release P/97/116, 6 February 199777 Fourth Renewables Order for England and Wales Offer, January 1997
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At the end of November 1996, 67 NFFO landfill gas projects were generating electricity, witha total capacity of 116 megawatts. Another 60 MW is expected to come on stream over thenext three years78.
Consistent with its policy of encouraging incineration of waste for energy recovery, theDepartment of the Environment's Energy from Waste booklet notes:
"Increasingly high environmental standards for landfill sites, reductions in the availablecapacity and the introduction of the landfill tax will all add to the cost of landfill, makingenergy from waste more attractive. Despite these factors, the cost gap in unlikely to closecompletely in the near future. However, under the Environmental Protection Act 1990, localauthorities, in their role as waste disposal authorities, are not required to accept the lowesttender for their contracts where an alternative offers environmental benefits (as set out in DOECircular 8/91)."
Which is the best environmental option will depend on local factors and the assumptionsmade in any formal "life cycle assessment", which measures the total environmental impactof products over their entire life cycle79. Library Research Paper 96/103 contains furtherinformation on landfill gas, and the impact of the landfill tax. The European Commission hasproposed a new version of the Landfill Directive, one provision of which would reduce thelandfilling of organic waste - a move which would lessen the potential of landfill gas as anenergy resource80. Landfill gas could supply 1.8% of current UK electricity demand, basedon a price of 5p per kilowatt-hour and a 15% real required rate of return. These figuresshould be taken only as indicative, partly because the accessible resource will depend on therelative proportions of waste being incinerated and landfilled. An ETSU publication81
provides information on the contributions which different renewables could make underdifferent assumptions of cost and discount rates.
78 DTI press notice P/96/879 27 November 199679 "The Application of Extended Life Cycle Assessment to Recycling and Waste Management" Global
Environmental Change Programme Briefings no. 11, March 199780 Croner Waste Management Briefing 3 December 199681 An Assessment of Renewable Energy for the UK, ETSU 1994 (HMSO)
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IV Sewage gas and animal wastes
So far this paper has focused on energy recovery from municipal waste, either in incineratorsor by tapping the gas emitted by landfill sites. Other forms of waste which can serve assources of energy include forestry residues, surplus straw, sewage, and animal wastes. Weend with brief discussions of sewage gas and animal waste.
A. Sewage gas
The bacterial digestion of sewage sludge produces methane which can be burned to produceheat and electricity. Sewage sludge is a by-product of sewage works and it consists of athick, putrescible, odorous liquid with about 4% solid matter. Thirty five million tonnes (wetweight) are produced annually. A significant proportion of the energy recovery is in the formof heat used, for example, to maintain optimum temperatures for anaerobic digestion.However, annual (UK) electricity generation from sewage gas amounts to some 120.2thousand tonnes of oil equivalent (1995 figures82).
Sewage gas schemes received support under the first two renewables rounds in England andWales (NFFO-1, NFFO-2): a total of 26 projects with a capacity of 33.31 megawatts, and a100% commissioning rate83.
B. Animal waste
Some animal waste, such as chicken litter, can be burned to provide heat and electricity.NFFO-4 includes, as one of its technology bands, the anaerobic digestion of agriculturalwastes. Six projects have been awarded contracts with a capacity of 6.6 megawatts, at anaverage price of 5.17 pence per kilowatt-hour84. The exclusion of purpose-built plants for theanaerobic digestion of municipal waste has been criticised on the grounds of its economicpotential; several local authorities have already ordered large scale plants85.
One example of an operating plant, which received NFFO-1 support, is given in chapter 4 ofRenewable Energy: Power for a sustainable future (Open University 1996). A 750 cubicmetre plant at Piddlehinton in Dorset can handle over 20,000 gallons of pig slurry a day. Thebiogas, mainly methane, which is produced is burned to produce roughly 750,000 kilowatt-hours annually for the National Grid. Purpose-built digesters such as this one have a varietyof environmental benefits. They reduce odours, destroy pathogens, displace fossil fuels,reduce methane emissions, and the residue can be used as a compost or fertiliser86.
82 Digest of United Kingdom Energy Statistics 1996 (DTI)83 Fourth Renewables Order for England and Wales Offer January 199784 DTI press release P/97/116, 6 February 199785 ENDS Report November 199586 CADDET Renewable Energy Newsletter March 1996
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V Further reading
• Energy from Waste: Getting more value from municipal waste Department of theEnvironment, November 1996
A summary of Government waste policy, which concentrates on incineration forenergy recovery from waste.
• RE View, DTI August 1994
A special issue which summarises the Government's strategy for new and renewableenergy
• Energy for the Future: Renewable Sources of Energy Communication from theCommission COM(96) 576 final, 20 November 1996
This Green Paper for a Community Strategy includes a comparison ofrenewable energy production in each member state.
• The Energy Report (volume 1): Change and Opportunity DTI 1996
Together with a companion volume dealing with oil and gas resources, The EnergyReport provides an annual overview of the energy industry in the UK. Chapter 10covers new and renewable energy.
• http://www.etsu.com/
The internet address of the ETSU home page. Formerly known as the EnergyTechnology Support Unit, ETSU is the Governments executive agency for energytechnologies.
• http://eeru-www.open.ac.uk/NATTA/r.o.l.html
An edited version of the news sections of Renew, the journal of NATTA, theindependent national UK 'Network for Alternative Technology and TechnologyAssessment'.
EnergyEnvironmental IssuesScience and Technology
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Recent Research Papers on related subjects include:
96/103 Landfill 08.11.96
95/85 Global warming: Environmental and Economic Effects 07.07.95
95/86 Global warming: Policy responses 14.07.95
95/50 The Environment Bill (HL) (Bill 85 1994/95) 12.04.95 93/83 Renewable Energy 29.07.93
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